ABSTRACT
Titanium substrates were subjected to severe plastic deformation using surface
mechanical attrition treatment (SMAT) in a high energy ball mill. Mechanical
treatments influence the microstructure and mechanical behaviour of the Ti-surface.
Moreover, partial amorphization takes place concurrently in the surface region.
Successive subdivision and amorphization finally results in the formation of well
separated nanocrystalline and amorphous phases in the near surface. Surface
mechanically treated Ti-substrates were characterized by X-Ray Diffraction (XRD)
and Atomic Force Microscopy (AFM). The average grain size of the nanocrystallites
is about 200nm after 10 min of SMAT, and about 18nm after 20 min. The
microhardness of the mechanically treated Ti-surfaces is improved as a result of
surface nanocrystallization. However, corrosion resistance of SMAT samples
decreases significantly compared to untreated Ti substrates. Contamination with Fe
and Cr were observed at the Ti-surface after SMAT. These particles could play an
important role in material strengthening and amorphization process.